David Lesher prodded the keyboard with:

John G writes:


I am amazed no one has suggested using a good old Simpson 260 or
similar ANALOGUE meter and get the real answer.

They do not read RMS either....

Here's a possible idea. Get a lamp, and a light meter.
Measure the brightness of the lamp when run from the line.
Repeat from the inverter.
Compare.

A incandescent lamp does not care what the waveform looks like; its
output is a function of the RMS voltage.


Actually that is a very good way to measure overall power. Radio hams
used to do just that to measure tramsmitter output.


--
Best Regards:
Baron.